Project team aims to develop
innovative harvesting and planting techniques

Denmark has made noteworthy strides in reducing nutrient
pollution, a problem that has decimated seagrass beds in its own coastal waters,
in Chesapeake Bay and other large estuaries, and in other near-shore ecosystems
worldwide.

Now, a $4.49 million grant to an international team that
includes researchers Robert “JJ” Orth, Ken Moore, and Scott Marion of William & Mary's Virginia Institute of
Marine Science will support efforts to develop innovative techniques and tools for
restoring eelgrass to areas where nutrient reductions have brought back the
clear, sunlit waters this underwater plant needs to thrive.

The five-year project, funded by the Danish Council for
Strategic Research, will be led by Erik Kristensen of the University of
Southern Denmark, in partnership with VIMS, other research centers in Denmark,
Sweden and the Netherlands; government agencies; and private businesses.

Orth—who leads an eelgrass restoration project in Virginia’s
coastal lagoons that ranks as one of the most successful in the world—says that
members of the “NOVAGRASS” team will “use small-scale tests to determine the
best techniques for harvesting, storing, and planting eelgrass seeds, then work
with industry partners to develop the equipment and logistics needed to scale
these techniques up for use in large-scale restoration efforts."

"This parallels
many of the successful techniques we’ve developed here in Virginia,” says Orth.

Seagrass restoration efforts

Seagrass restoration efforts are planned or in operation in
coastal zones around the world, as citizens and governments begin to recognize
the many economic and ecological services that seagrasses provide. Seagrass
meadows offer nursery habitat and feeding grounds for fish and shellfish,
protect shorelines from erosion, and help improve water quality by absorbing
excess nutrients and trapping suspended particles.

Kristensen says the impetus for the NOVAGRASS project comes
from the findings of prior studies by his own team, Orth’s Seagrass Monitoring
and Restoration Program and Moore’s shallow-water monitoring work at VIMS, and
other seagrass research groups around the world.

“Our previous REELGRASS study revealed that the expected
recovery of eelgrass following reductions in nutrient loading hasn’t occurred,”
says Kristensen, “even in areas where government regulations and voluntary
actions during the last few decades have significantly reduced the runoff of
nitrogen and phosphorous into Danish waters.” An integrated effort in the
watershed that feeds Denmark’s Odense Fjord has reduced nitrogen inputs by up
to 25 percent, and inputs of phosphorous by about 75 percent. Nutrient reductions limit the
algal blooms that can otherwise block the sunlight that seagrasses need for
photosynthesis.

Negative feedback

Moore and Orth say that natural recovery in areas where
human activities have reduced eelgrass cover is limited by negative feedback
mechanisms that hinder or delay the transition from seeds to established
seedlings. Moore compares the situation to the difficulties a homeowner might
encounter when trying to re-establish grass by seeding a bare patch of dirt, as
opposed to re-seeding thin spots within an existing expanse of healthy lawn.

Kristensen says the negative-feedback mechanisms include wave
action and the effects of drifting seaweed.

“Both of these can destroy eelgrass
seedlings,” he says, “either directly by ballistic impact and shading or
indirectly by stirring up sediments that then limit the amount of light
reaching the seafloor.”

Kristensen notes that eelgrass recovery can also be hampered
by a marine worm called Arenicola marina,
which commonly invades former eelgrass meadows, where it’s burrowing and feeding
can bury seeds too deep for germination, and dislodge any seedlings that have
begun to emerge.

Another factor, he says, is the organic enrichment of
seafloor sediments that often accompanies the over-fertilization that first contributes
to seagrass decline. This enrichment reduces the sediments’ anchoring capacity,
making eelgrass seedlings more likely to be displaced by currents.

Kristensen and Orth have high hopes for the NOVAGRASS project,
noting that it builds on lessons learned during earlier research and
restoration work, including Orth’s ongoing efforts in Virginia’s coastal
lagoons.

Orth and his staff will host a number of the Danish
colleagues in 2013, when they travel to Virginia to observe many of the successful
techniques employed by Orth and Moore in their restoration work in the region.

“The successes seen in the U.S. and Holland reveal the need
for careful consideration of site selection, water quality, and the scale of restoration,”
says Kristensen. “These projects also show that restoration techniques must be
developed specifically for the environmental conditions in each marine location
where eelgrass restoration is attempted.”

“Recognizing the importance of seeds in developing new beds
as well as stressors and bottlenecks that deter seedling growth is a big help for
developing the techniques and tools needed for future large-scale restoration
efforts,” says Orth.

Orth and Moore just returned from a meeting in Denmark where
they shared the results of their research with university and governmental
officials.